Synthesis and characterization of ultra-long silica nanowires.

Large-scale synthesis of amorphous silica nanowires was achieved by using simple physical evaporation of a mixture of Si and Al2O3 powders. Scanning electron microscopy observations showed that the silica nanowires have lengths of several mm and diameters of 20-100 nm. X-ray photoelectron spectroscopy revealed that these nanowires consisted of Si and O elements in an atomic ratio of approximately 1:2, consistent with the stoichiometric formula SiO2. Photoluminescence measurements showed a blue luminescence band in the wavelength range of 400-500 nm with three peaks at 420 nm, 440 nm, and 470 nm, respectively, which also differs from the previous reports of the photoluminescence for oxygen-deficient silica nanowires. This may suggest that the fully oxidized silica nanowires still have many structural defects that contribute to the photoluminescence. [ABSTRACT FROM AUTHOR]